Simulating Magic Eye Tubes With Spinning LEDs and Simple Electronics

So-called "magic eye" tubes are display devices, which indicate signal level by the projection of wedge-shaped shadows on a glowing view screen. They were developed in the 1930's for use as tuning indicators in radio receivers, and as alternatives to the then-expensive-to-manufacture meter movements.

Because they haven't been produced in decades, and because they degrade and wear out with use, the supply of functional eye tubes is dwindling. I thought there might be value in coming up with a potential substitute-- something that acted like an eye tube that could replace them in applications like antique radio restoration and general experimentation.

It turns out that convincing eye tube behavior can be simulated with one or more LED's mounted on a rotating disk. The electronics to drive the LEDs amounts to little more an an op-amp, a transistor, and some timing components.

This video demonstrates the appearance of a real eye tube in operation, and introduces the principles involved in simulating one through electro-mechanical means. The video shows that the display generated by the electro-mechanical equivalent can be fairly convincing.

Be sure to visit my web site as additional details will appear there in coming weeks.

www.hpfriedrichs.com

Category:

Science & Technology

Tags:

• antique
• radio
• ham
• magic
• eye
• tube
• owl
• cat's
• display
• POV
• mechanical
• television
• LED
• electronics
• science
• experimentation

[basspig]

Very nice. Now if you can adjust the frontporch timing as well as the backporch timing, you'd pretty much have it duplicated.

[ac7zl]

@basspig

I've given that some thought. I think this could easily be done by using the timing signal to generate a triangle wave verses the sawtooth used in the prototype.

[ThreeRsMom]

Once you have an 8-pin chip in the system, you may as well use a microcontroller, which makes RDCST's wish for a more "lifelike" single-wedge display a mere matter of programming. The Microchip PIC12F675 has an ADC, a timer, and several GPIO pins, and can be had for a few dollars. I'll try it sometime.

Dave Wise

[ac7zl]

@ThreeRsMom

I've worked with PIC chips in the past and agree that there aren't too many problems that can't be solved through the application of a microcontroller. On the other hand, ownership of a chip programmer and assembler or compiler, and knowledge of how to use them, represents a barrier to a lot of people. The solution presented is simple to build and make functional.

[RDCST]

It look great, but need one more improvement; the real magic eye looks more like a green pacman so it closes in the same point.

I think you can resolve this by using just one LED and changing the times in order to reach the 360º = 100%

[ac7zl]

@RDCST

Yes and no... there are many flavors of eye tube. The "real" tube demonstrated in the video is the "Pacman" type, but the LED version represents a model more like the 6X6 or EM31. Two refinements easily added would be a current source to charge the cap, and a current sink to discharge it. This would give you a linear triangle wave (instead of a non-linear sawtooth). The display would then become even more convincing.

[ferencproject]

nice work

[OMGABUSE100]

Soooo postin this on Facebook!!

[rEdf196]

It would be cool to see virtual magic eye displays for SDRs software defined radios for computers I have seen many examples using virtual 70s style analog meters and bar graph types. perhaps an I-pod style 3D screen displaying the traditional green colour to pschidellic multicolour changing effects the eye effects could be round, square, triangular or any shape imaginable. Just a few ideas I had.

[Subaro0o]

you are a genius, u make kip kay look gay

[rrabit44]

would like to see an update

[carpespasm]

Very nicely done! Perhaps drilling out some "window" holes in the metal support in the front where it goes over the display to allow more of it to be seen in the middle could be done? I don't imagine it needs the full strength of that metal.

[johnsprostock]

FULL COMPLETE DOUBLE MACARONI!!!!!

[CorruptReverend]

Have you considered replacing the top support arm with some sort of bearing embedded into the end of the tube (perhaps a simple graphite cup)? This would rid your design of the blocked out line in the display.

[protelboy]

Brilliant idea! Super interesting and inventive.....great work.